A context-compaction handoff is persisted as an ordinary history message
but is not a real turn. The ACP history replay streamed it as a bare
user/agent message chunk, dropping the in-process _compressed_summary
marker, so ACP frontends (editors, vscode-hermes) rendered the entire
handoff as a regular message.
Tag replayed summary chunks under _meta.hermes (ACP's extensibility
channel), covering all three persistence shapes the compressor emits:
- standalone role="user" handoff -> compactionSummary: true
- standalone role="assistant" handoff (alternation-driven role pick)
-> compactionSummary: true
- merge-into-tail message (preserved tail content + appended summary)
-> containsCompactionSummary: true, a distinct key so clients that
collapse standalone summaries cannot hide the preserved real content
Detection honors the in-process metadata flag and falls back to a new
ContextCompressor.classify_summary_content() content classifier
(standalone/merged/None), so it also works for a DB-reloaded session
that lost the in-memory flag. _is_context_summary_content is now a thin
wrapper over the classifier, keeping existing callers unchanged.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Israel Lot
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